1. Field of the Invention
The present invention relates to a divided chamber type diesel engine.
2. Description of the Prior Art
Generally a divided chamber type diesel engine includes a cylinder head provided with a divided chamber while a main combustion chamber is formed within a cylinder. An injection hole is formed in the cylinder head eccentrically to a center axis of the cylinder so as to descend at an angle toward the center axis of the cylinder.
In one of such engines, a pair of valve recesses are formed concavely in a top surface of a piston. In this engine, since a volumetric ratio of the valve recesses relative to an entire volume of the main combustion chamber becomes comparatively large when its piston is near to a top dead center position, a lot of air accumulates locally within the valve recesses and a combustion expanding gas injected from the injection hole can be mixed effectively so as to improve combustion performance. Actually, however, the combustion performance is not so much improved in comparison with an engine having no valve recesses. It is supposed that the reason is that the mixing between the air within the valve recesses and the combustion expanding gas is not carried out effectively.